ISP port blocking practice

[jda at tapodi.net (Jon Auer)]

> With all the different webmail systems, it seems unlikely to me (though I definitely wouldn't say impossible) that bots are spamming through your webmail (unless you work for gmail, hotmail, etc. and are an attractive enough target that it made sense to code a bot to automate utilizing your webmail interface). ?Bots being used as proxies seems far more likely to me for the general case of "bots" spamming through an ISP's webmail.
>

Many providers and hosts use the same webmail packages so the work to
automate is a bit lower than one might think.
We have seen bots sending spam using our squirrelmail and roundcube
webmail using credentials gleaned from phishing activity.